In an image forming apparatus such as an electro-photographic copying machine, a facsimile, and a printer, for ordinary paper in a specific size with high frequency in use, sheets of paper are supplied using a paper supply cassette. While for sheets of paper or sheet films with low frequency in use, sheets are generally supplied using a manual paper supply tray. When supplying sheets of paper using the paper supply tray, various kinds of sheets of paper supported by the paper supply tray are taken out by paper supply rollers, and then while being guided by a relay guide, the sheets of paper are conveyed toward separation conveying rollers and then register rollers. The paper supply tray, to prevent the sheets of paper on the conveying path from the paper supply tray to the register rollers from skewing, has a side guide slidable for controlling the width of sheets on the sheet support face.
However, for thick paper stiffer than ordinary paper, there is a fear that the side guide may be defeated and moved by a load due to skewing of sheets during paper supply. As a result of movement of the side guide like this, the sheets may be skewed. Further, for sheets in a comparatively small size such as a postal card or a playing card, sheets taken out from the paper supply tray by the paper supply rollers come out from the side guide before reaching the separation conveying rollers. As a result, after passing the side guide position, the sheets may be skewed.
Therefore, conventionally, there is an apparatus available for installing a stopper on the side guide or controlling the slidability of the side guide, thereby preventing the side guide from moving due to a load of sheets. Further, conventionally, there is an apparatus available for supplying sheets in a small size from a close position by the separation conveying rollers and reducing skewing of the sheets coming out from the side guide.
However, in the conventional apparatus, the sheet width is controlled only by the side guide installed on the paper supply tray, so that after passing the side guide position, it is impossible to correct skewing. Therefore, due to skewing caused after passing the side guide, there is a fear that conveying defects such as jamming of sheets and bending of front ends may be caused. Further, when sheets are skewed, it is necessary to greatly arrange the sheets by the register rollers. Therefore, arrangement by the register rollers cannot be executed sufficiently, thus there is a fear that the image quality may be lowered due to an image displacement.
Therefore, a sheet conveying device and an image forming apparatus for surely preventing sheets taken out from the paper supply tray from skewing, guiding the sheets in the separation conveying direction free of skewing. Thereby preventing various kinds of sheets from defective conveying, surely arranging the front ends of the sheets at the position of the register rollers, and forming a good image on the sheets are desired.